Contents

Landing on Earth, now a barren, desolate planet, Sarah, Harry and the Fourth Doctor are unaware of the large, watching robot. The robot is the work of Styre, a Sontaran warrior, who uses all humans landing here for his experimental programmes.

What has happened to the other space explorers who have come here? Why is the Sontaran scout so interested in Earth and is brutally torturing humans, including Sarah Jane? Will the Doctor, be able to prevent an invasion and certain disaster, and save both Earth and his companions?

Unlike the televised story, in which the Doctor, Sarah, and Harry use Space Station Nerva's transmat to come down to Earth, they come down in the TARDIS, which is then accidentally returned to Nerva by the transmat.

Nerva is consistently referred to by the Doctor and other characters as "Terra Nova".

Despite being called Styre on the back cover, within the text the Sontaran refers to himself as Sontaran Military Assessor Styr.

After falling down a hole, the Doctor has a dream about rats chewing their way into the TARDIS.

Harry initially believes the Sontaran to be a Golem.

The Sontaran robot is called a Scavenger and is described as hovering and octopus-like. It is much more sophisticated than the version seen in the televised story (probably owing to the limitations of a television budget).

Styr's energy weapon is built into his armour, and described as "concealed" by the armour.

The Sontaran ship is much larger than the ones seen in the televised version, and a description of its interior as multi-chambered is given. It is also apparently patrolled by smaller versions of the Scavenger.

Much of Erak and Krans' parts are exchanged, making Krans the more aggressive character. (He is described as big and burly, whereas on screen he is below average height.)

The Doctor falls down the crevice when the Scavenger lassoes Sarah and Roth while they are lowering him with his scarf.

Zake dies when the Scavenger stops him short with a lasso and causes him to break his neck, rather than falling down a crevice.

Styr is referred to several times as having an inky black breath.

Styr's experiment on Sarah is more elaborate, with her hallucinating drowning, being burned alive in a desert and attacked by a horde of ants. She is imprisoned in a cave rather than tied to a rock, and when Harry enters the cave he is affected too, imagining himself being attacked by a demonic Sarah. The experiment has already begun when Harry first finds her.

There is an extra scene of the Doctor meeting Harry and finding out about the Sontarans before going off to find Sarah. (A version of this was scripted but apparently not filmed.) The Doctor is briefly trapped in the force-field at the cave mouth.

Styr's superior is referred to as the Controller rather than the Marshal. It is revealed that Styr is delaying submitting his report because he is enjoying the experiments.

On screen, Roth refers to two Galsec crewmen killed in the experiments as Heath and Speer. Here, both Roth and Krans refer to Warra and Henk instead.

The Doctor and Styr start their fight unarmed and both later use the gravity bar as a weapon.

Styr kills Vural by knocking him over a cliff edge rather than stabbing him. He then throws the Doctor off the edge but he survives because part of the Scavenger's levitation system slows his fall.

The Doctor weakens Styr during the fight by pouring the contents of a hip-flask into his probic vent.

The Doctor speculates that the Sontarans are trying to occupy Earth for its terullian deposits formed by the solar flares and later discovers it is part of an alliance with another cloned race, the Hyperioi. There is no mention of the war with the Rutan as on screen.

Ian Marter suggested novelising this two-parter which no-one else was interested in doing.

Marter also portrayed the character of Harry Sullivan in the story. He had previously adapted The Ark in Space, in which he had also appeared. These two books are unique as being, to date, the only examples of a Doctor Who actor adapting his own TV stories. Marter would go on to write numerous other novelisations for Doctor Who before his death in 1986 (with posthumous publications continuing for more than a year thereafter).

This was the first time a two-episode story was adapted for a novel. It established it was possible to expand the somewhat scant material of a two-parter into a full-length novel, opening the door for later adaptations of the other two-parters in the series. (Tying between Doctor Who and the Ark in Space)